*{
    margin: 0;
    padding: 0;
}
.top {
    background: #99a9bf;
    height: 60px;
}
#if{
    width: 100%;
    height: 100%;
}




#app {
    width: 100%;
    height: 685px;
    background-size: cover;
    background-repeat: no-repeat;
}